The Answer for the Origin of Life? Maybe!

I started reading The Vital Question: Energy, Evolution, and The Origin of Life, by biologist Nick Lane, due to recommendations by famed physicist Sean Caroll, and by Bill Gates. I’d like to add my small voice to their choir: go read this book. It’s one of the best best books I’ve read.

In The Vital Question, Nick Lane sets out to answer two of life’s biggest questions: what is the origin of life, and what is the origin of Eukaryotic (complex) life. Along the way, he also addresses the origin of two sexes, ageing, and more. And when I say “answer the question”, I don’t mean do a literary review and float some wild theories; I mean actually developing very-detailed new ideas and testing them with mathematical models and actual experiments. This is extremely impressive.

This is a popular science book, and it’s written well. Nick Lane manages to talk about the biology in the needed detail to get his ideas across, while still describing things vividly and cleaving off unnecessary detail. I was particularly impressed by his description of the goings-on inside the mitochondrion:

Shrink yourself down to the size of an ATP molecule, and zoom in through a large protein pore in the external membrane of a mitochondrion. We find ourselves in a confined space, like the engine room of a boat, packed with overheating protein machinery, stretching as far as the eye can see. The ground is bubbling with what look like tiny balls, which shoot out from the machines, appearing and disappearing in milliseconds. Protons! This whole space is dancing with the fleeting apparitions of protons, the positively charged nuclei of hydrogen atoms. No wonder you can barely see them! Sneak through one of those monstrous protein machines into the inner bastion, the matrix, and an extraordinary sight greets you. You are in a cavernous space, a dizzying vortex where fluid walls sweep past you in all directions, all jammed with gigantic clanking and spinning machines. Watch your head! These vast protein complexes are sunk deeply into the walls, and move around sluggishly as if submerged in the sea. But their parts move at amazing speed. ….

…all sound and fury, signifying… what? You are at the thermodynamic epicenter of the cell, the site of cellular respiration, deep within the mitochondria. Hydrogen is being stripped from the molecular remains of your food, and passed into the first and largest of these giant respiratory complexes, complex I. …. If you, an ATP, were as big as a person, complex I is a skyscraper. … It amounts to a wire, insulated by proteins and lipids, channeling the current of electrons from ‘food’ to oxygen. Welcome to the respiratory chain!

In most of the book he is less picturesque, but his style remains both informative and interesting. He explains a lot of biological detail, but not as a textbook but rather as part of explaining the chain of causation of how things work (according to his theory). And he shares how his theories evolved and changed through his research.

The writing can get quite technical at times, and there were sections I found hard to follow. And Nick Lane has a habit of repeating himself; this ain’t necessarily bad when you’re hammering in new ideas into your reader’s mind, and assuming the reader might not remember all that he read in the previous chapter. Both of these “flaws” don’t detract from the clarity and engagement of the writing, and the glorious reveal of finding out how life and complex life arose.

And yes, I do think he has found the right answers. At least broadly. Of course, the research is not yet conclusive, and I’m not a biologist so maybe I’m missing some glaring flaws in his arguments – but to my uneducated ears he sounds very persuasive. Part of this, surely, is his heavy emphasis of the aspect of energy and physics as constraining and directing the evolution of life. I’ve been attracted to this idea for years now, and Nick Lane brings it to bear in a wonderfully imaginative and meticulous way.

So what is the answer, then? What is the origin of life, and of complex life?

Nick Lane strongly argues for the idea that life requires an energy gradient, and that this has to be a proton-gradient as all life is based on using proton-gradients as a source of energy. He identifies alkaline hydrothermal vents (white chimneys) as the only viable source of such energy and conditions, and discusses his attempts to recreate this early pre-biotic evolution in his lab. Following early chemical evolution within the tiny vesicles in these hydrothermal vents, the proto-cells developed membranes and proton pumps that could generate an artificial proton-gradient, and thus life was free to escape the vents and colonize the entire world.

And what of Eukaryotes? Well, these emerged when in a freak accident one bacterium swallowed another without killing either in the process. This is not a new idea, but Nick Lane adds some new twists to it. He explains in detail why handling the proton gradient requires local attention by locally-available genes, yet bacteria’s method of sex and duplication does not allow them to make such local genes available. The symbiosis between the swallowed bacteria and its host, however, allowed the swallowed bacteria to take up this role, leading to its evolution into the mitochondrion. In the process, virtually all characteristics of the eukaryotic cell evolve: its massive genome, filled with introns, the nucleus, chromosomes, and more.

Finally, Nick Lane goes on to explain why the evolution of specialized tissues led to the evolution of a soma (body) and germline (eggs and sperm), two sexes, and ageing. All of this is heavily influenced by the co-evolution of the mitochondrial genes and the genes in the nucleus, and Lane points out various implications and supporting evidence for this, including why birds are the perfect species (well, perfect in how their mitochondrial DNA matches their nuclear DNA, which means they live longer, have fewer genetic diseases, and can exert themselves much further).

Again, I’m not a biologist. But a lot of what Nick Lane says makes sense to me. Even if the details will turn out wrong, I think in broad strokes he’s right. I suspect he found the core process behind the evolution of life and of complex life (I’m less sure about the whole sex thing). Which is huge.

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